England need to be 'bulletproof' to win 2019 Rugby World Cup

Paul Gustard insists England are intent on becoming the best defensive team in the world -- a quest that begins when Argentina visit Twickenham on Saturday.

Eddie Jones' men open their autumn schedule in search of a ninth successive victory over the Pumas amid a challenge from assistant coach Gustard to become the meanest side in the game.

"We want to have the best defence, whatever percentage increase that equates to I don't care," Gustard said. "I want the best defence in the world and I've told that to Eddie and told that to the team. Eddie wants me to deliver the best defensive team in the world.

"Any team that wins the World Cup, apart from the last one when the best attack also won, has the best defence. Going into the World Cup we need to be bulletproof, trust each other, have confidence in each other, be adaptable, confrontational and absorb pressure when our attack isn't firing."

Gustard has revealed that Sam Underhill will be England's defensive leader despite having only made his debut in June against Argentina.

The 21-year-old averages 15 tackles a match for Bath this season and has the opportunity to stake a long-term claim to the openside duties following James Haskell's loss of form and Tom Curry's autumn-ending wrist injury.

"It's important that Sam stamps some authority in that area though action and direction," Gustard said. "Sam's style of play suits what we have been looking at from a seven. James Haskell performed that role brilliantly for us and what expect from Sam is a dominant performance.

"He's not a Haskell in terms of how he talks, thankfully, as there's a bit of air space for other people but his action is excellent. He is a physical player has stopping power, can hit people backwards and take momentum away in attack. He prides himself on stopping people with force.

"On the other side of the ball he must clear out efficiently and effectively. We expect him to go up another level against Argentina."

Curry was due to provide cover for Underhill from the bench only for the Sale flanker to be ruled out on Thursday afternoon by the dislocated wrist sustained in training, creating a space in the 23 for Sam Simmonds.

"It was an innocuous injury -- he was contesting for the ball and caught his arm," Gustard said. "It was a freak accident and he is a resilient player and with that injury he said he is going to have the best squat in the competition.

"It's a great opportunity for Sam, who has had a great season. It's very exciting and it is his birthday today [Friday] -- what greater gift than his first cap?" England face Argentina for the final time before their pivotal group showdown at the World Cup in 2019.

When asked if they want to make a statement on Saturday, Gustard said: "Massively. "All we have spoken about is Argentina and we have had three results against them in the last 12 months. We are confident going into this game."